1. Field of the Invention
The invention is extenders for optical path segments particularly in an optical correlator system having reflective and transmissive optical components positioned along a folded optical axis or path.
2. Description of the related Art
The reflective optical correlator system as disclosed in the related application, supra, includes a planar support body having an irregular perimeter with a plurality of system stations formed at selected locations along the irregular perimeter of the support body. A plurality of reflective optical components are positioned at selected system stations. A coherent light beam traverses a folded optical axis or path tunneled within the planar body and bounded or defined by the reflective optical components.
The planar body of this extremely compact reflective optical correlator system is preferably formed from a ZERODUR.TM. material which maintains all of the optical components in a fixed and stable configuration with respect to each other over various hostile environments such as vibration and temperature variations. Coupled with its excellent mechanical rigidity, ZERODUR material also has excellent machining and polishing properties.
The folded optical path within the ZERODUR body has several sequential path segments. The length of a path segment can be the same as or be different from another path segment, and each can be accurately determined by the desired dimensions of the output correlator pattern traversing the optical path. The total length of the folded optical path (the sum of the lengths of the individual path segments) is determined by the required optical distances between the optical components.
But the fact that ZERODUR material has excellent mechanical rigidity and machining properties can have a disadvantage; an adverse production affect.
It is well known that production of an item or component for use in a system becomes cost effective when the item or component can be replicated as a standard item or component in production quantities rather than in the custom production of a single item or component in the very extreme situation.
Although the effect of reflective optical components on the light beam passing through the optical path segments can not be disregarded, it is the more noticeable effect of transmissive optical components that affect the quantity production of standardized planar blocks.
Transmissive optical components, virtually without exception, affect the light beam passing therethrough because of the index of refraction of the material that forms the component; typically a near optically pure transparent material such as clear glass. Regardless of the dimensional specifications for such transmissive optical components, any slight variation in a dimension such as thickness can affect the index of refraction. And this can affect the required length of a particular optical path segment associated with the optical component.
However, the standardized planar blocks in production quantity can not individually compensate for or correct these relatively slight variations in the index of refraction of any one transmissive optical component.